The present invention relates to a semiconductor device and a method for manufacturing the same and more particularly to a semiconductor device with an electrical fuse and a method for manufacturing the same.
In the past, laser trimming has been known as a technique for repairing a defective circuit in a semiconductor device manufacturing process, in which the defective circuit is switched to a previously prepared backup redundant circuit. Laser trimming is performed by irradiating a fuse on a wafer with laser light. More specifically, the circuit is repaired by melting a specific fuse among plural fuses as polysilicon or metal wires by laser irradiation.
In recent years, with the increasing tendency towards highly functional systems or large capacity memories, there has been a demand for semiconductor devices called SIP (System In Package) in which a plurality of semiconductor chips are housed in one package. In this type of semiconductor device (SIP), in order to increase the yield in final testing after laser trimming, it is necessary to make a repair after molding of the semiconductor chips. However, if laser trimming is performed on the wafer, it is difficult to make a repair after molding of the semiconductor chips. In addition, a special device for cutting (blowing) fuses is needed in laser trimming.
Therefore, there is an increasing need for an electrical fuse which is cut not by laser irradiation but by applying current to it. Among documents which disclose such electrical fuses is Japanese Unexamined Patent Publication No. 2007-73576. In the technique disclosed therein, since an electrical fuse is cut by applying current to it using the internal power supply in a semiconductor chip, it can be cut in an on-wafer state even after molding.
In the past, polysilicon wires, which are widely used for interconnect wires in semiconductor devices, have been adopted for electrical fuses. A polysilicon wire electrical fuse is cut by electromigration. More specifically, when current is applied to the electrical fuse, metal silicide migration occurs and the resistance of the fuse changes. While the resistance before cutting is 100 to 200 ohms, the resistance after cutting is in the range of several kilo-ohms to several mega-ohms and one-to-four digit higher than before cutting.